Hello all,
I not terribly familiar with building rpms and I have inherited an rpm
build setup. My job is to debug and build rpms that someone else
previously built.
The rpm that I have to rebuild has been changing ownership of /usr from
root to the user that is supposed to own the rpm's files (we'll call
that user "build". Using rpm2cpio, I found that the rpm is creating
/usr/src/debug. As a result both /usr and /usr/src are suddenly owned
by build.
I noticed that in the build process, /usr/lib/rpm/find-debuginfo.sh was
being called and that seems to deal with /usr/src/debug, but nowhere in
the spec file do I see ownership of /usr/src/debug being specified.
Any ideas?

You are likely missing
%files
%defattr(-,root,root)
to change the default ownership for all files to root.root.
And the package manifest is likely including /usr (which is perhaps
unnecessary).
hth
73 de Jeff